1. Field of the Invention
The present invention relates to a recording medium library apparatus and, more particularly, to a magnetic tape library apparatus having a magnetic tape cartridge direct entry and exit mechanism.
2. Description of the Related Art
Magnetic tape units are one of several diverse kinds of external storage devices for use with computers. The magnetic tape units operate most commonly on what is known as the open reel system using 0.5-inch wide tapes. The chore of manually loading the open reels have been alleviated by widening acceptance of automatic tape loading devices. With these devices, the operator need only set a desired tape reel onto a receptor which then causes the tape to be loaded automatically. Today, operators' burdens are further alleviated by the widespread use of magnetic tape cartridges. A magnetic tape cartridge, accommodating a tape having the same width as that of open reel tapes, allows the tape to be threaded out of the enclosed reel for automatic tape loading.
A plurality of such magnetic tape cartridges needed are entered in a magnetic tape library apparatus. Any one of the cartridges is selected and loaded to a magnetic tape drive unit for data recording and reproduction. Conventional magnetic tape library devices include a cell unit having a plurality of cells each accommodating a magnetic tape cartridge; a magnetic tape drive unit for recording and reproducing data; and an accessor for automatically switching magnetic tape cartridges between cell unit and magnetic tape drive unit. The currently known magnetic tape library devices further include a cartridge entry unit for entering magnetic cartridges into the library apparatus, and an automatic cartridge exit unit for automatically ejecting magnetic tape cartridges from inside the library apparatus.
An accessor transports magnetic tape cartridges through the magnetic tape drive unit, cell unit, cartridge entry unit and automatic cartridge exit unit. Magnetic tape library apparatuses of this kind are widely used as an external mass storage device for computers. These apparatuses are required to operate unfailingly when unattended.
The cartridge entry unit mentioned above transports one by one a plurality of cartridges entered by the operator up to a predetermined position. There, the accessor receives each cartridge and stores it into the appropriate cell of the cell unit. One disadvantage of the prior art magnetic tape library apparatus using this cartridge entry unit is that it takes time to store a large number of cartridges into the cell unit.